- Flavinium and Alkali-Metal Assembly on Sulfated Chitin: A Heterogeneous Supramolecular Catalyst for H2O2-Mediated Oxidation
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Heterogeneous multiple-catalyst assemblies were developed in which the flavinium cation and Na or Li cations were easily immobilized on a chitin-derived anionic polymeric scaffold through noncovalent ionic interactions. The supramolecular flavinium catalysts were successfully employed in the environmentally friendly heterogeneous Baeyer–Villiger oxidation and sulfoxidation by H2O2. Owing to the cooperative catalytic effect of flavinium, alkali metal, and sulfated chitin, the supramolecular flavinium assembly showed higher catalytic activity for the Baeyer–Villiger oxidation of cyclic ketones than the corresponding homogeneous flavinium catalyst. Because the ionic assembly was stable under the reaction conditions, the catalyst could be readily recovered by simple filtration and reused.
- Sakai, Takuya,Watanabe, Mirai,Ohkado, Ryoma,Arakawa, Yukihiro,Imada, Yasushi,Iida, Hiroki
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Read Online
- Synthesis method of butyrolactone compound
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The invention relates to a synthesis method of a butyrolactone compound. The synthesis method comprises the following step: in the presence of a solvent and a cobalt catalyst, converting an oxetane compound shown as general formula I into a butyrolactone compound shown as general formula II through carbonyl insertion ring expansion reaction in an atmosphere of CO and H2. Compared with an existingmethod for synthesizing butyrolactone through oxetane carbonylation ring expansion reaction in a carbon monoxide atmosphere, the synthesis method of a butyrolactone compound provided by the inventionhas the advantages of excellent catalytic activity, excellent chemical selection, wide substrate applicability, mild reaction conditions and the like; compared with other methods for synthesizing butyrolactone compounds, the method provided by the invention has the advantages of wide substrate range, high atom economy, no need of noble metal catalysis and the like, therefore the method has a wideapplication prospect.
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Paragraph 0019-0054; 0055
(2020/07/21)
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- Efficient Synthesis of γ-Lactones by Cobalt-Catalyzed Carbonylative Ring Expansion of Oxetanes under Syngas Atmosphere
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A practical route from oxetane or thietane to γ-(thio)butyrolactone via solvated-proton-assisted cobalt-catalyzed carbonylative ring expansion under syngas atmosphere has been established. A wide variety of γ-(thio)butyrolactones can be afforded in good to excellent yields. The versatility of this method has been well demonstrated in the synthesis of intermediates towards the natural product Arctigenin as well as the pharmaceuticals Baclofen and Montelukast. The observed promoting effect of glycol ether solvent has been rationally interpreted.
- Tang, Yitian,Shen, Chaoren,Yao, Qiyi,Tian, Xinxin,Wang, Bo,Dong, Kaiwu
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p. 5898 - 5902
(2020/10/02)
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- Total synthesis and stereochemical assignment of nostosin B
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Nostosins A and B were isolated from a hydrophilic extract of Nostoc sp. strain from Iran, which exhibits excellent trypsin inhibitory activity. Nostosin A was the most potent natural tripeptide aldehyde as trypsin inhibitor up to now. Both R- and S-2-hydroxy-4-(4-hydroxy-phenyl)butanoic acid (Hhpba) were prepared and incorporated into the total synthesis of nostosin B, respectively. Careful comparison of the NMR spectra and optical rotation data of synthetic nostosin B (1a and 1b) with the natural product led to the unambiguous identification of the R-configuration of the Hhpba fragment, which was further confirmed by co-injection with the authentic sample on HPLC using both reversed phase column and the chiral AD-RH column.
- Wang, Xiaoji,Feng, Junmin,Xu, Zhengshuang,Ye, Tao,Meng, Yi,Zhang, Zhiyu
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- Lactonization reactions through hydrolase-catalyzed peracid formation. Use of lipases for chemoenzymatic Baeyer-Villiger oxidations of cyclobutanones
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A one-pot chemoenzymatic method has been described for the synthesis of γ-butyrolactones starting from the corresponding ketones through a Baeyer-Villiger reaction. The approach is based on a lipase-catalyzed perhydrolysis for the formation of peracetic acid, which is the responsible for the ketone oxidation. Optimization studies have been performed in the oxidation of cyclobutanone, finding Candida antarctica lipase type B, ethyl acetate and urea-hydrogen peroxide complex as the best system. The relative ratio of these reagents has also been analyzed in depth. This synthetic approach has been successfully extended to a family of 3-substituted cyclobutanones in high substrate concentration, yielding the corresponding lactones with excellent isolated yields and purities, under mild reaction conditions and after a simple extraction protocol.
- González-Martínez, Daniel,Rodríguez-Mata, María,Méndez-Sánchez, Daniel,Gotor, Vicente,Gotor-Fernández, Vicente
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- Synthesis and antibacterial activity of novel 2-oxo-pyrrolidinyl oxazolidinones
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Novel antibacterial oxazolidinones bearing pyrrolidinone ring system at the C-5 side chain were synthesized and their in vitro antibacterial activities were evaluated. Most of the synthesized oxazolidinones showed good antibacterial activity against the G
- Bhattarai, Deepak,Lee, Sun Hee,Kim, Hyeong Kyu,Kang, Soon Bang,Pae, Ae Nim,Kim, Eunice Eunkyeong,Oh, Taegwon,Cho, Sang-Nae,Keum, Gyochang
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scheme or table
p. 1310 - 1316
(2012/07/14)
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- Synthesis of chiral five-, six-, and seven-membered heterocycles from (S)-3-hydroxy-γ-butyrolactone
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Chiral small molecules such as amino alcohols and their heterocyclic derivatives are useful building blocks for asymmetric synthesis and the preparation of biologically active compounds. Using a common starting material derived from carbohydrate, the (S)-3-hydroxy - butyrolactone, we have synthesized several five-, six-, and seven-membered nitrogen-containing chiral heterocycles. These include (S)-3-benzyloxypyrrolidine, a protected 6-substituted morpholin-3-one and its homologous 1,4-oxazepan-3-one, and 6-trityloxymethyl tetrahydro-1,3-oxazine-2-thiones. These chiral small heterocycles were synthesized from the lactone via efficient cyclization reactions. Their syntheses and characterization are reported here. Georg Thieme Verlag Stuttgart - New York.
- Yang, Hao,Goyal, Navneet,Ella-Menye, Jean Rene,Williams, Kristopher,Wang, Guijun
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experimental part
p. 561 - 568
(2012/05/05)
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- HIV Integrase Inhibitors
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The disclosure generally relates to the novel compounds of formula I, including their salts, which inhibit HIV integrase and prevent viral integration into human DNA. This action makes the compounds useful for treating HIV infection and AIDS. The invention also encompasses pharmaceutical compositions and methods for treating those infected with HIV.
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Page/Page column 79
(2009/10/17)
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- Nitrile biotransformations for the synthesis of highly enantioenriched β-hydroxy and β-amino acid and amide derivatives: A general and simple but powerful and efficient benzyl protection strategy to increase enantioselectivity of the amidase
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(Chemical Equation Presented) Biotransformations of a number of racemic β-hydroxy and β-amino nitrile derivatives were studied using Rhodococcus erythropolis AJ270, the nitrile hydratase and amidase-containing microbial whole cell catalyst, under very mild conditions. The overall enantioselectivity of nitrile biotransformations was governed predominantly by the amidase whose enantioselectivity was switched on remarkably by an O- and a N-benzyl protection group of the substrates. While biotransformations of β-hydroxy and β-amino alkanenitriles gave low yields of amide and acid products of very low enantiomeric purity, introduction of a simple benzyl protection group on the β-hydroxy and β-amino of nitrile substrates led to the formation of highly enantioenriched β-benzyloxy and β-benzylamino amides and acids in almost quantitative yield. The easy protection and deprotection operations, high chemical yield, and excellent enantioselectivity render the nitrile biotransformation a useful protocol in the synthesis of enantiopure β-hydroxy and β-amino acids.
- Ma, Da-You,Wang, De-Xian,Pan, Jie,Huang, Zhi-Tang,Wang, Mei-Xiang
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p. 4087 - 4091
(2008/09/20)
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- Mechanistic divergence of two closely related aldol-like enzyme-catalysed reactions
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The mechanistic divergence of two closely related aldol-like enzyme-catalyzed reaction is studied. The interaction of threose 4-phosphate with 3-deoxyerythrose 4-phosphate with 3-deoxy -D-arabino-heptulosonate 7-phosphate synthase (DAH7PS) revealed previo
- Ahn, Meekyung,Pietersma, Amy L.,Schofield, Linley R.,Parker, Emily J.
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p. 4046 - 4049
(2007/10/03)
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- Microwave-assisted cleavage of Weinreb amide for carboxylate protection in the synthesis of a (R)-3-hydroxyalkanoic acid
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A versatile route for the modular synthesis of (R)-3-hydroxyalkanoic acids, constituents of the naturally biodegradable poly(3-hydroxyalkanoate) polymers, and its application to the synthesis of (R)-3-hydroxydecanoic acid is described. Key steps include a microwave-assisted catalytic transfer hydrogenation and a facile microwave-assisted hydrolysis of an N-methoxy-N-methyl (Weinreb) amide, which enhances the practicality of this protecting group for carboxylic acids.
- Jaipuri, Firoz A.,Jofre, M. Francisca,Schwarz, Kimberly A.,Pohl, Nicola L.
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p. 4149 - 4152
(2007/10/03)
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- A ring closing metathesis-osmylation approach to oxygenated oxepanes as carbohydrate surrogates
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A ring closing metathesis (RCM)-osmylation sequence has been developed for the formation of highly oxygenated cyclic ethers from the corresponding acyclic dienes. A systematic examination of various substrates in this reaction revealed that the process is general in scope and is insensitive to the number of alkoxy substituents present. Subsequent osmylation of the metathesis product proceeds with excellent diastereoselectivity to furnish highly oxygenated oxepanes. These oxepanes represent one-carbon homologated carbohydrates.
- Wong, Jerome C. Y.,Lacombe, Patrick,Sturino, Claudio F.
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p. 8751 - 8754
(2007/10/03)
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- Asymmetric synthesis of malic acid-type synthons VIA chiral norephedrine-derived oxazolidines
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Polyoxygenated C4 synthons 5-7 are synthesized in enantiomerically pure form starting from ephedrine derived oxazolidines 2,4 and 13. The 1,4-benzylate addition to 2 and 4, the key step in the synthesis of 5 and 6, proceeds cleanly with almost
- Bernardi, Anna,Cardani, Silvia,Scolastico, Carlo,Villa, Roberto
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p. 1987 - 1998
(2007/10/02)
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- HIGHLY REGIOSELECTIVE RING-OPENING OF α-SUBSTITUTED CYCLIC ACID ANHYDRIDES CATALYZED BY LIPASE
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Lipase Amano P irreversibly catalyzed a ring-opening of α-substituted cyclic acid anhydrides 1 preferentially at the less hindered carbonyl group to give monoesters with high regioselectivity.
- Hiratake, Jun,Yamamoto, Kazuyoshi,Yamamoto, Yukio,Oda, Jun'ichi
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p. 1555 - 1556
(2007/10/02)
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- Ruthenium Complex Catalyzed Regioselective Dehydrogenation of Unsymmetrical α,ω-Diols
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Ruthenium complex catalyzed regioselective dehydrogenation of unsymmetrically substituted 1,4- and 1,5-diols in the presence of such a hydrogen acceptor as α,β-unsaturated ketone gave predominantly β-substituted γ-lactones and γ-substituted δ-lactones, respectively.Among the ruthenium complexes, RuH2(PPh3)4 was the most active and selective catalyst and showed high catalytic activity even at 20 deg C.For example, 2,2-dimethyl-1,4-butanediol was quantitatively converted to dihydro-4,4-dimethyl-2(3H)-furanone and dihydro-3,3-dimethyl-2(3H)-furanone in a ratio of 99.6/0.4 in the presence of 4-phenyl-3-buten-2-one (hydrogen acceptor) and a catalytic amount of RuH2(PPh3)4 at 20 deg C.The proposed main factor controlling the regioselectivity is the steric constraints produced by the substituent(s) of a diol at the coordination step of alkoxy group to ruthenium.
- Ishii, Youichi,Osakada, Kohtaro,Ikariya, Takao,Saburi, Masahiko,Yoshikawa, Sadao
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p. 2034 - 2039
(2007/10/02)
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